In a semiconductor device manufacturing process, predetermined processes such as film forming, etching and so on are performed on semiconductor wafers as substrates to be processed. In addition, in a flat panel display (FPD) manufacturing process, predetermined processes such as film forming, etching and so on are performed on glass substrates for FPD. These processes use a multi-chamber type substrate processing apparatus including a plurality of process chambers in which the predetermined processes are performed on the substrates. The use of this substrate processing apparatus allows the substrates to be subjected to a plurality of processes in a consistent atmosphere.
However, in the semiconductor device and FPD manufacturing processes, in some cases, different kinds of processes may be consecutively performed in the substrate processing apparatus. A series of processes is feasible by a combination of a plurality of process chambers having different conditions. For example, two different kinds of processes are feasible in succession by a combination of a process chamber in which a process is performed on the substrates under a condition and a different process chamber in which a different process is performed on the substrates under a different condition.
Japanese Patent Application Publication No. 2003-221671 discloses a technique in which a Ti film as a contact layer and a TiN film as a barrier layer are formed in a contact hole. In the technique disclosed in Japanese Patent Application Publication No. 2003-221671, a multi-chamber type film forming system including two Ti film forming apparatuses for forming the Ti film by chemical vapor deposition (CVD) and two TiN film forming apparatuses for forming the TiN film by CVD is used to form these films. The Ti film formation is performed by loading a wafer in the Ti film forming apparatuses. The TiN film formation is performed by loading the wafer on which the Ti film is formed in the TiN film forming apparatuses.
Reaction products are attached and deposited in inner walls and parts of the process chambers in which processes such as film formation and etching are performed. Such attachments may be peeled off and attached, as particles, to the substrates, which leads to deterioration of quality of articles.
In order to remove such attachments, there is a need to clean the interiors of the process chambers. Cleaning of the process chambers in which the film formation is performed is carried out by keeping the process chambers at a predetermined temperature and then supplying a cleaning gas such as ClF3 gas, NF3 gas or the like into the process chambers. After the cleaning, for the purpose of making constant process conditions to first and subsequent wafers W of a subsequent process, pre-coating is carried out to deposit a thin film in the process chambers. Processes for maintenance of environments in the process chambers, including such cleaning and pre-coating, are called “conditioning.” Regular performance of such conditioning can prevent particles from being generated. A cycle of performance of the conditioning is varied depending on conditions of film formation and etching.
In the multi-chamber type substrate processing apparatus including the plurality of process chambers, conditionings are performed at respective timings in respective process chambers. The timings at which the conditionings in the process chambers are performed are not necessarily synchronized with each other. In particular, if different kinds of film forming processes are consecutively performed in combinations of plural process chambers having different film forming conditions, since cycles of performance of conditionings are varied from one process chamber to another, timings at which the conditionings in the process chambers are performed are not synchronized with each other. When the different kinds of film forming processes are consecutively performed and the timings at which the conditionings in the process chambers are performed are not synchronized with each other, there arise the following problems. In this case, first, while a conditioning is being performed in a process chamber in which a film forming process is performed (hereinafter referred to as a “previous process chamber”), a substrate cannot be transferred from the previous process chamber to a process chamber in which another film forming process is performed later (hereinafter referred to as a “posterior process chamber”), so that the film forming process for the substrate is not feasible. In addition, while a conditioning is being performed in the posterior process chamber, the substrate cannot be transferred from the previous process chamber to the posterior process chamber, so that the film forming process for a next substrate is not feasible.
Thus, while a conditioning is being performed in one of the plurality of process chambers, the film forming process for the substrate is not feasible in a separate process chamber related to the process chamber in which the conditioning is being performed. Therefore, a throughput (the number of substrates that can be processed for a unit time) of each process chamber is lowered by the sum of a time period required in the conditioning of the process chamber and a time period required in the conditioning of the separate process chamber. As a result, the overall throughput of the substrate processing apparatus is lowered.